Draft equalizing stack head with rain guards



Feb. 19, 1957 w. o. MORAN 2,781,716

DRAFT EQUALIZING STACK HEAD WITH RAIN GUARDS Filed Feb. 2, 1955 '2 Sheets-Sheet 1 INVENTOR William 0.Moran/ ATTORNEYS Feb; 19, 1957 w. o. MORAN DRAFT EQUALIZING STACK HEAD WITH RAIN GUARDS 2 Sheets-Sheet 2 Filed Feb. 2, 1955 A INVENTOR VVilh'wnv OJVoI-a/m ATTORNEYS DRAFT EQUALIZING STACK HEAD WITH RAIN GUARDS William O. Moran, Tulsa, Okla. Application February 2, 1955, Serial No. 485,795

2 Claims. (Cl. 98-58 I My invention relates to improvements in the structure of the stack head of chimneys and exhaust stacks to provide for equalizing the draft therein regardless of outside wind conditions and to prevent rain from entering such stack heads. This invention is a continuation-in-part of my co-pending application Serial No. 313,568, filed October 7, 1952, now Patent No. 2,701,999, which is a division of my U. S. Patent 2,656,833, issued October 27, 1953, said patent being a continuation of application Serial No. 689,231, filed August 8, 1946, now abandoned.

it is the object of my invention to provide a stack head structure that will eliminate draft fluctuation caused by wind direction and forces, thus providing a controlled raft resulting in increased efficiency of the boiler,'heater, or chamber which discharges into exhaust stack or chimney having a stack head structure according to my invention, and to provide in such a stack head rain guards for intercepting and draining outward from the stack head any rain.

A further object of my invenion' is to provide a head structure in a chimney or exhaust stack that will keep the draft constant and hold the fire in the firebox of the boiler or'furnace connected thereto and at the same time preventing the entrance of rain into the chimney or exhaust stack. I

A still further object of my invention is to provide a chimney or exhaust stack for a boiler or furnace which is constructed with'its top end open but having the adjacent vertical side walls therebelow pierced with a plurality of orifices or ports preferably in uniform spaced relationship and having suflicient area to permit free movement of exhaust gases from the chir'nney or exhaust stack and incorporating in the top rain guards which are withinthe stack or chimney and adjacent the apertures.

Another object of my invention is toprovide a chimney or exhaust stack for a boiler or furnace which is constructed with its top end imperforate but having the adjacent vertical side walls therebelow pierced with a plurality of orifices or ports preferably inuniform spaced relationship and having sufiicient area to permit free movement of exhaust gases from the chimney or exhaust stack and incorporating in the top-thereof rain guards which are I enclosed within the stack or chimney ancl adjacent the apertures.

Another object of my invention is to providea cap for telescopic mounting into or' onto the top end of a chimney or exhaust stack ofaboiler or furnace or other chamber wherein the capis constructed with an open top end but has the adjacent vertical side Walls 'therebelow pierced with a plurality of orifices or ports preferably in uniform spaced relationship and having sufficient area to permit free movement of exhaust gases from the chimney, exhaust stack, or compartment and to incorporate rain guard elements within thecap and adjacent the apertures to intercept any rain and drain it out through said apertures.

A further object of my invention is to provide a cap for telescoping mounting" into or onto-thetop end of a 2. chimney or exhaust stack of a boiler or furnace wherein the cap is constructed with an imperforate top end but has the adjacent vertical side walls therebelow pierced with a plurality of orifices or ports preferably in uniform spaced relationship and having suflicient area to permit free movement of exhaust gases from the chimney or exhaust. stack and to incorporate rain guard elements within the cap and adjacent the apertures to intercept any rain and drain it out through said apertures.

A still further object of my invention is to provide a heating unit with an equalizing stack head in order to maintain an equalized or uniform draft, and prevent down draft, regardless of direction and amount of wind pressure that may occur at the stack head and in carrying out this operation to also provide means to prevent entrance of rain into the stack head without impairing the usefulness of such equalizing stack head.

Another object of my invention is to provide a ventilator for any type of structure where ventilation is needed but where excessive ventilation is undesirable, such as would be caused by high winds moving across the conventional type of ventilator or where relative winds blow against the ventilator or are caused to blow there- 'against and to incorporate in said ventilator without materially diminishing its efliciency interior bafiles to drain out any rain entering such a ventilator. O Other objects and advantages of the invention will be evident from the following detailed description read in conjunction with the accompanying drawing.

This type of ventilator or stack head is highly desirable 'for use with oil field type boilers, heaters, gas and other type fuel heating equipment. This type of device is also highly desirable for use as ventilators for closed compartments and can be installed on trucks, planes, trains, or ships, as the speed of the conveyance, plus the speed of the wind, will not changethe draft through the stack head and with the incorporation of the rain guard, rain is prevented from entering such stack head without decreasing the efficiency of the apparatus.

For a more complete understanding of the nature and scope of my invention, reference may be had to the accompanying drawings in which: I

Fig. 1 is a side view of one form of draftcqualizing stack head according to my invention;

Fig. 2 is a vertical elevation along line 2-2 of Fig. 1;

Fig. 3 is an elevation in plan along line 3-3 'of Fig. 1;

Fig. 4 is a fragmentary enlarged side elevation showing the juncture of the lower thimble and the upper shell in Fig. 2 of the draft equalizing stack head;

Fig.5 is a side elevation of a'modified view of the draft equalizing stock head adapted to fit over the end of a stack;

Fig. 6 is a vertical cross sectional view along line 6--6 of Fig. 5; I i

Fig. 7 is a sectional plan view along section 7-7 of Fig. 5; and

Fig. 8 is a diagramatic illustration of the dnaft equalizing stack head shown in Fig. 5 installed on a chimney .of a heater.

Throughout the various filgures and description like reference numerals refer to similar parts.

In my co-pending applicationSerial No. 313,568 filed on October 7, 1952, and entitled Draft Equalizing Stack Head, the theory of operation of this draft equalizing stack head is developed. p

In addition to the operation of the draft equalizing stack head described in my co-pcnding application, there are two conditions which may dictate the size of the stack head and aperture area therein and the number of horizontal rows of apertures. Where a chimney or vertical stack is designed for a full capacity of the boiler or boilens with which it may be used, then the total area of the apertures in the draft equalizing stack head must be sufiicient to adequately permit exhaust gases to exit therethrough. In the case of a chimney orexhaust stack which is oversized for the equipment with which it is-used, then the total area of the apertures may be decreased since they do not have to accommodate such an exit capacity of exhaust gases and thus the exhaust stack head may be smaller. Thus, the equipment, the size of thestacks and the amount of equipment to be used dictates to some degree the size of the stack head and the consideration which must be given to the total aperture area which will provide for sufiicient exit of exhaust gases. At the same time, the criterion is to provide for still day eiiiciency for the given set of conditions for a particular chimney or exhaust stack and the equipment with which it is used.

In carrying out the above considerations, provision is made to intercept and drain away any rain which may enter through the draft equalizing apertures in the stack head.

In Fig. 8 I have shown a diagrammatic outline of a heater generally indicated at 10 having a firebox 11 having a burner 12 over which is positioned a horizontal baffie plate 13 providing an exhaust chamber 14 that is connected to an exhaust stack 15 having an upper end 15 to which is attached a draft equalizing stack head generally indicated at 16 according to my invention.

The stack head generally indicated at 16 is shown in Figs. 5, 6 and 7 and will be described later.

The draft equalizing stack head shown in Figs. L4 is generally indicated at 17 and comprises 'an annular vertically extending elongated shell 18 having a greater horizontal cross sectional area than the thimble 19 to which it is attached at its lower end. Thimble 19 is telescopically received in the upper end of a chimney or exhaust stack 20 as shown in Fig. 2, in broken lines. The elongated shell 18 is attached to the upper end of thimble 19 by an annular ring that also serves as a rain guard elemeat which will be described hereinafter.

The vertically extending elongated shell 18 is formed with a plurality of horizontal rows of apertures 21 which are spaced apart in a vertical direction in a uniform manner as indicated in Fig. l. In the representation shown in Fig. 1, there are seven rows of apertures which apertures are indicated at 22 and these are staggered from horizontal row to horizontal row in their orientation. Reference to Fig. 3 shows aperture 22 having opposite exposed aperture 22 diametrically therefrom. Each of the other apertures has an oppositely disposed aperture and similar arrangement to the apertures 22-22, typically shown in Fig. 3. In the representation shown in Figs. 1-3 there are 10 apertures and they have a uniform equal area. While I have shown circular apertures 22, these apertures may take other shapes. The total area of the apertures is sufficient to provide still day efficiency for the draft in the stack or chimney to which the draft equalizing stack head is attached regardless of the direction and force of the wind blowing against the draft equalizing stack head.

The upper end of the shell 18 is indicated at 23 while the bottom end is indicated at 24. The bottom end 24 is slipped over the upper end of the thimble 19 and rigidly secured thereto by means of the combination rain guard and support element 25. a

Reference to Fig. 4 shows that the rain guard is an annular ring-like member whose lower end 25 abuts the interior periphery of the shell 18 adjacent the bottom of the apertures 22 and is secured to the interior of shell 18 by welding indicated at 28. The upper end of the rain guard 25 is attached as at 25" to the outer upper end of the thirnble 19. Thus, the rain guard 25 slopes upwardly and inwardly toward the vertical axis Y-Y' extending through the draft equalizing stack head and this axis coincides with the axis of the vertical flue therethrough. In Fig. 4 it will be observed that aperture 22 has a vertical height A, as indicated, and the vertical projection of the rain guard 25 is indicated at B. It will be noted that the vertical projection B is less than the height of the aperture 22 as indicated at A. Through the difference in height between A and B there is provided a spacing for a free flow of air and exhaust gases through the aperture 22 yet the rain guard 25 intercepts any impinging rain coming through the aperture 22. The rain is intercepted on the upper surface 25s of rain guard 25 and drains down to the lower portion of the aperture 22 and out to the outside of the elongated shell 18.

I have indicated, see Figs. 1 and 2, that the upper end 23 of the elongated shell 18 has attached thereto a top 26 as by the welding 27. While a top is here shown, it is possible to utilize the draft equalizing stack head without a top but at a decrease in efficiency.

Referring to Fig. 2, it will be noted that the rain guards above the bottom rain guard 25 are of a like construction wherein they extend upwardly toward the central axis YY and theirvertical projections on the outer shell, as indicated at B, in Fig. 4, are less than the vertical height of the apertures 22 thereadjacent.

The modified form of draft equalizing stack head is shown in Figs. 5-7 in detail. It consists of an elongated vertical shell 32 having a plurality of vertically spaced aparthorizontal rows of apertures generally indicated at 33, said apertures being indicated at 34. These rows of apertures 33 are spaced substantially uniformly and vertically from each other and in the representation shown in Figs. 5 and 6 the apertures in each row are spaced directly above each other as contrasted with the staggered relationship in each adjacent row shown in Figs. 1 and 2 of the first form of draft equalizing stack head described above. Shell 32 of annular elongated shape has a top 35 afiixed thereto and, as in the case of the draft equalizing stack head 17, it may be used without this top but at a decrease in etficiency. Spaced apart apertures 37 are formed in the base of the elongated shell 32 and have attached thereto bosses 36 which are apertured and threaded to receive said screws 38 that secure the cap or draft equalizing stack head 16 in adjusted position on the top end 15' of a typical stack 15 as shown in Fig. 8.

As in the draft equalizing stack head 17, rain guards 39, similar to rain guards 25, are here provided as shown in Fig. 6. These rain guards are annular continuous ring-like members having their bottom edge 39' secured as by welding to the inner surface of the shell 32 adjacent the bottom of the apertures 22 in each row. The vertical projection of the plate 39 is indicated at B and is of a less height than the vertical height A of the apertures 34. A free fiow of exhaust gases and air may pass out through or in through the apertures 23 and at the same time any rain impinging therethrough is intercepted by the annular rain guards 29 except that it drains down and out the aperture 34.

Thertotal area of the apertures 34 provide for a free flow of exhaust gases from the stack or chimney to which the draft equalizing stack head is attached.

The draft equalizing stack head or draft stabilizing device whether built into the top of a chimney or exhaust stack or fabricated as a unit and placed thereon afford for that stack and equipment connected therewith operation as though for a still day regardless of wind force and direction acting on the stack head or device. When the wind blows toward the stack head from any particular direction it shortens the flow of stack gases flowing from the upwind side of the stack, and lengthens the flow of the stack gases flowing from the downwind side of the stack head. As the velocity of the wind continues to increase, the flow of stack gases leaving the stack continues to shorten on the upwind side of the stack head and to lengthen on the downwind side, until the wind pressure and the stack pressure are equal, at which time, the upwind side of the stack head is virtually sealed oil. The pressure on the inside of the stack head and the outside pressure on the upwind side of the stack head being equal, there can be no movement of stack gases out of the upwind side of the stack head nor of wind into the upwind side of the stack head. When the wind pressure exceeds the stack pressure, the wind blows into the upwind side, and through the stack head. This supplies the additional air demanded by the reduced pressure or-the vacuum on the downwind side of the stack head. As the wind increases in velocity, the amount of the wind blowing through the stack head increases, in direct proportion to the increase demand, on the downwind side of the stack head. This whole action creates a still day zone at the top of the stack, and maintains still day conditions at the top of the stack at all times regardless of direction or velocity of the wind acting on the stack head.

When the wind pressure exceeds the pressure of the exhaust gases inside the stack head, the wind flows into the apertures thereof on the upwind portion, mixes with the rising exhaust gases, and then flows out through the apertures at the opposite side, the downwind portion.

In order to make the draft equalizing stack head or draft stabilizing head more effective during rainy weather, rain guards as discussed above have been installed and in effect rain-proof the stack head to make it additionally effective for the purpose for which it so efliciently serves.

I claim as my invention:

1. A draft equalizing stack head adapted to vertically surmount the flue of a chimney, said stack head having a vertical tubular wall forming a flue therein, an open bottom end, an imperforate top thereon, said bottom end being adapted to be connected with the top of the chimney so that the flue of the chimney is in communication with the flue of said stack head, means for securing said stack head to said chimney, said vertical tubular wall having a plurality of horizontally disposed rows of apertures therethrough, said rows being spaced substantially uniformly from each other, each of said apertures being of uniform area, said top being spaced from the topmost horizontal row of apertures therein and forming with the adjacent vertical tubular wall above said topmost horizontal row of apertures a capacity chamber, a rain guard for each horizontal row of apertures comprising an annular plate having its bottom edge abutting the inner surface of the vertical tubular wall and attached thereto so that the bottom edge is in alignment with the bottoms of said apertures and inclining upwardly toward the center of the flue in the vertical tubular wall a distance such that the vertical projection of said plate on said vertical wall is less than the vertical aperture proximal thereto so that rain striking said plate is drained out through said apertures adjacent said annular plate, the total area of said apertures being sufiicient to permit free movement of exhaust gases from the chimney as determined for stillday operating conditions for said chimney, whereby when wind blows against one apertured portion of the stack head, the vacuum created at the opposite apertured portion of the stack head is offset by the wind flowing through the apertures in the first portion to the apertures in the second portion, whereby the action of the wind regardless of direction or velocity in acting on any apertured portion of the chimney does not change the uniform draft of still-day operating conditions in said chimney.

2. A draft stabilizing device for mounting in the top of a chimney to project vertically upward from the chimney, comprising a thimble adapted to be telescopically received within the top end of the chimney, an annular and vertically extending elongated shell having a horizontal cross sectional area greater than said thimble, the vertically extending wall of said elongated shell having a plurality of horizontally disposed rows of apertures therethrough, said rows being spaced substantialy uni-' formly from each other, each of said apertures being of uniform area, a rain guard for each horizontal row of apertures comprising an annular plate having its bottom edge abutting the inner surface of the vertical tubular wall and attached thereto so that the bottom edge is in alignment with the bottoms of said apertures and inclining upwardly toward the center of the flue in the vertical tubular wall a distance such that the vertical projection of said plate on said vertical wall is less than the vertical height of the aperture proximal thereto so that rain striking said plate is drained out through said apertures adjacent said annular plate, means rigidly connecting the shell with the upper end of said thimble comprising the lowermost one of said annular rain guards having its top edge secured to the top of said thimble and its bottom edge secured to the inner wall of the surrounding elongated shell in alignment with the bottom edges of said apertures in the bottommost horizontal row in the shell, the total area of said apertures being sufficient to permit free movement of exhaust gases from the chimney as determined for still-day operating conditions for said chimney, whereby when wind blows against one apertured portion of the elongated shell, the vacuum created at the opposite apertured portion of the elongated shell is offset by the wind flowing through the apertures in the first apertured portion to the aligned apertures in the second portion whereby the action of the wind regardless of direction or velocity in acting on any apertured portion of the elongated shell does not change the uniform draft of still-day operating condition in said chimney.

References Cited in the file of this patent UNITED STATES PATENTS 182,681 Knight Sept. 26, 1876 1,583,196 Stewart May 4, 1926 1,930,050 Hilt Oct. 10, 1933 2,309,255 Rowland Jan. 26, 1943 FOREIGN PATENTS 466,283 Great Britain May 26, 1937 

